Mar 17, 2021, 3:42 PM
Post #1 of 7
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Heading performance with static line
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Hi,
In the place I live we don't have a lot of high walls, but plenty of static line jumps. This and the fact that I'm newbie means that this kind of jump is the most frequent.
Until not long ago I thought that every static line jump will almost certainly have an excellent heading opening. BUT, recently I witnessed 2 different jumps that resulted in a 100º right and 160º left off-heading. Both jumps were done using a long extension cord, approximately 30 feet (the tree was far away from the edge of the cliff). Just to be clear: tree->extension cord->2 break cords->bridle. In both cases the jump was done by experienced jumper, good body symmetry and very light, almost no wind conditions that shouldn't affect the opening. They managed to solve the situation and landed safely.
Speaking with several people we came up with 2 hypothesis for the possible cause: 1. Too long extension cord can cause undesirable cord movement which can affect the opening direction of the canopy. 2. If the extension cord is not strictly rigid and have some elasticity it could "shake" the package during the extraction and bring on an off-heading.
Thinking about the later, I remembered the Apex static line bridle that has en elastic portion precisely to absorb the initial load created by canopy extraction. So I guess the elasticity shouldn't be a problem? Anybody here using it could share his experience? And any thoughts about using long extension cord?
Mar 25, 2021, 10:20 AM
Post #3 of 7
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Re: [giacomo] Heading performance with static line
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Hi giacomo,
I did a sketch to illustrate the situation, side and top view.
The anchor is directly behind the jumper, no strange angles, jumping forward.
Not using any bungee, but the extension cord (paracord 550 type III) itself stretches a bit. This is only visible applying some good force and when the cord is long.
Mar 25, 2021, 11:04 AM
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Re: [Faraway] Heading performance with static line
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Thank you for the sketches. Did they tie the break cord loops both on the centre of the bridle or one was attached at the end of it?
If they are both in the middle, I think that there's no time for the paracord to move because of its elastic return. If one is close to the PC it'd be possible that the slack is enough to let it move around.
Mar 30, 2021, 9:20 AM
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Re: [Faraway] Heading performance with static line
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Hi,
For a time I was doing a lot of SL jumps rappelling about 40 feet on a 10mm dynamic (stretches) climbing rope and using it as the tie off. At the time I asked several experienced mentors if I should switch to static (non stretching line) and got the consensus that if anything the stretch will help with staging deployment. Did many jumps that way without issues.
Static line off headings are rare but happen. Crosswinds are an obvious factor. As others are stating having everything from tie off down through the system in line with push direction/intended opening heading is imperative.
I have heard off one ~150 off heading on a PCA where the deployment was captured on the giver's camera. I would share if I had it. It appeared an ear of the packjob crossed the bridle in a way that rotated the packjob on extraction. Not to sideline into a packing conversation but curious if anyone has comments on that as a factor?
static_with_extension.png
